Clip May Work for Risky Mitral Valve Patients

Action Points

Explain that the MitraClip device delivered through a percutaneous procedure may provide a benefit for patients with severe mitral regurgitation and a high surgical risk, according to a non-randomized study.

Point out that the survival rate at one year was higher in patients who received the device compared with patients with a similar burden of comorbidities who received either medical therapy or surgery.

Patients with severe mitral regurgitation who are at high surgical risk drew benefit from a device called a MitraClip, delivered through a percutaneous procedure, a nonrandomized study showed.

Among patients considered too high risk for inclusion in the EVEREST II trial, the MitraClip device improved clinical symptoms, quality of life, and left ventricular function through one year, according to Patrick Whitlow, MD, of the Cleveland Clinic, and colleagues.

In addition, the survival rate at one year was higher in patients who received the device compared with patients with a similar burden of comorbidities who received either medical therapy or surgery (76.4% versus 55.3%, P=0.047), the researchers reported in the January 10 issue of the Journal of the American College of Cardiology.

"These data and an acceptable rate of major adverse events suggest that placement of the MitraClip device is relatively safe and feasible in these high-risk patients," they wrote.

Surgical mitral valve repair or replacement is the gold standard treatment for symptomatic patients with severe mitral regurgitation, but many patients have a high burden of comorbidities that places them at high risk for surgery. Those who cannot undergo surgery receive medical therapy.

EVEREST II evaluated a third option, the MitraClip device, which is delivered percutaneously. After initially promising results for the device, the two-year results favored surgery for the prevention of death, mitral valve surgery, and/or re-operation for severe mitral regurgitation.

The trial also included a nonrandomized high-risk study arm (Endovascular Valve Edge-to-Edge Repair High Risk Study) to evaluate the use of the MitraClip device in symptomatic patients with severe mitral regurgitation (grade 3+ to 4+) with a risk for perioperative mortality of 12% or greater.

The researchers retrospectively recruited a comparator group of patients who were screened for the high-risk study but were not enrolled.

Of the 78 patients who underwent the MitraClip procedure, more than half had previous cardiac surgery, 59% had functional mitral regurgitation, and 41% had degenerative mitral regurgitation. MitraClip devices were successfully placed in all but three patients.

Of the 36 patients in the comparator group, 86% received medical management and 14% underwent surgery.

At baseline, the predicted 30-day mortality rate in the MitraClip group was 18.2% according to comorbidity burden and 14.2% according to the Society of Thoracic Surgeons score. The corresponding values in the comparator group were 17.4% and 14.9%.

The actual 30-day mortality rate was 7.7% in the MitraClip group and 8.3% in the comparator group. The difference was not statistically significant.

The most common major adverse event that occurred within 30 days was transfusion of two or more units of blood (17.9% of patients).

Through one year of follow up, there were improvements on several outcomes in the MitraClip group.

In surviving patients, 77.8% had a mitral regurgitation grade of 2+ or less by one year.

There were improvements in left ventricular end-diastolic and end-systolic volume and reductions in mitral annular dimensions, which suggests "that MitraClip therapy results in early reverse of left ventricular remodeling," according to the researchers.

In addition quality of life and New York Heart Association functional class improved, and the annual rate of hospitalization for congestive heart failure dropped.

Although the 12-month survival rate was significantly greater in the MitraClip group than in the comparator group, the researchers noted that a direct comparison between the two groups should be done with caution because of limitations in the recruitment of the comparator patients.

Those limitations represent a major weakness of the study, Zoltan Turi, MD, and Michael Rosenbloom, MD, of Cooper University Hospital in Camden, N.J., wrote in an accompanying editorial.

"More than 50% [of the comparator patients] were screen failures and did not meet anatomic criteria, noninvasive data were not read by the core laboratory, a number did not have eligibility assessed by transesophageal echocardiography, patients were selected retrospectively and included only a subset of those eligible, the sample size was small, events were not adjudicated by the clinical events committee, and no information is provided on patient management or any other outcomes parameter except survival," they wrote.

In addition, the reporting of 12-month echocardiographic and functional data was done for surviving patients only, which "can result in the reader overinterpreting the benefits of MitraClip in this patient population," Turi and Rosenbloom wrote.

They said that a PARTNER-like approach to examining the MitraClip device in patients at high surgical risk, and in those deemed inoperable, would be needed before routine adoption of the device for high-risk patients.

"However, every cardiologist follows patients who are disabled with or dying of this disease, with limited survival and without a suitable alternative to medical therapy," they wrote.

"The preliminary results of the EVEREST High Risk Registry suggest that the percutaneous approach has a reasonable enough risk-to-benefit ratio that it should continue to be available, albeit only if performed under investigational protocols by operators skilled at transseptal puncture and working in institutions with extensive experience in percutaneous structural heart interventions as well as a proven track record with mitral valve repair in at least moderate-risk patients," they said.

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